In evaluating research to test the hopelessness theory and Beck's theory of depression, we have arrived at a very disturbing conclusion: the various research strategies used to test these theories do not provide an adequate test of their basic postulates and may produce results that mislead investigators about their validities. In our view, the problems associated with past research strategies result, in part, from investigators' failure to appreciate the full methodological implications of the kinds of causal relations specified in the cognitive theories and, as a corollary, the heterogeneity that may exist among the depressive disorders. Indeed, researchers have not appreciated that these cognitive theories actually hypothesize the existence in nature of an, as yet, unidentified subtype of depression - "negative cognition depression." Thus, the overarching goal of this collaborative grant is to provide a more powerful test of the hopelessness theory's and Beck's theory's predictions regarding the etiology and subsequent course of negative cognition depression and a validation of this subtype of depression. To this end, we plan to conduct a large scale, two-year prospective study designed to test the etiological hypotheses of the cognitive theories of depression. In the Vulnerability Study, 420 currently nondepressed, non- psychopathological individuals who are at either high, medium or low risk for depression based on their cognitive styles will be followed prospectively for 2 years, on a monthly basis, with independent and blind self-report and interview assessments of stressful life events, cognitions and psychiatric status/symptomatology in order to predict onsets and subsequent relapses/recurrences of depression. These studies will contribute to the scientific understanding of the etiology of a subset of the affective disorders, to more valid nosology of the depressive disorders and to the development of interventions for treating and preventing the negative cognition subtype of depression.